Hidden bacteria and fungi discovered on da Vinci’s drawings
Leonardo da Vinci is famous for his elaborate, nuanced artworks and advanced technological ideas.
But recent research has revealed another level of complexity to his drawings: a hidden world of tiny life forms. The findings could help build a microbiome ‘catalogue’ for artwork. Each of the pieces had a uniqueenough collection of microbes that researchers could identify it again later purely from a study of its microscopic biology. And the drawings’ microbiomes had enough key elements in common to help researchers spot counterfeits based on differences in their microbiomes, or even authentic drawings that had been stored in different conditions over the centuries. The researchers also showed that da Vinci’s drawings had a significantly different microbiome than expected, with lots of bacteria and human DNA, likely a consequence of centuries of handling by art restorers and other people. Microbes known to make paper degrade over time were also present, showing why those restorers’ efforts had been necessary.
Researchers examined the microscopic biological material, living and dead, in seven of the master’s ‘emblematic’ drawings and found an unexpected diversity of bacteria, fungi and human DNA. Most of that material probably landed on the sketches well after da Vinci’s death, so the majority of DNA likely comes from other people who have handled the drawings over the centuries and not the polymath himself. But the newfound biological materials do have a story to tell.
The biggest surprise was the high concentration of bacteria in the drawings, especially when compared with fungi. Past studies have shown that fungi tend to dominate the microbiomes of paper objects such as these drawings, but in this case an unusually high amount of bacteria from humans and insects – likely flies that pooped on the paper at some point – were present. “Altogether the insects, the restoration workers and the geographic localisation seem to all have left a trace invisible to the eye on the drawings,” the researchers said. “[But] it is difficult to say if any of these contaminants originate from the time when Leonardo da Vinci was sketching its drawings.”
Most of that DNA likely came from people who have restored the work, starting in the 15th century. The team has not analysed the genetic material in the level of detail necessary to see who specifically it might have come from.
The researchers used a new tool called nanopore, a genetic-sequencing method that quickly breaks down and analyses genetic material, to make the detailed study of the different biological materials. The same researchers have studied artistic microbiomes in the past to determine how statues that were recovered from smugglers had been stored while they were in hiding. Going forward, the researchers said, this technique could reveal new details of the histories of even well-studied artworks.